Unit 1.5 Atomic Theory
The development of early models of the atom is discussed,
beginning with atomism 400 B.C., to models of Greek philosophers,
to Daltons first atomic theory.
Video program cues: 31:40-33:40

The early understanding of the atom

Link

A timeline of atomic
theory from Democritus to the 1950s with links
to important scientists and discoveries.

History of the atomic theory

"[Democritus:] Everything was composed of
atoms, which moved randomly in a vacuum, in a void. They
collided into each other by chance. This was the absolute
negation of Aristotle's idea that everything had a purpose
as divinely ordained [the theory of the Four Elements]."